forensic ballistics reviewer
Forensic Ballistics

Forensic Ballistics Reviewer 
Definition of Terms

ACP - Automatic Colt Pistol

Action - the working mechanism of a firearm. An action is a physical mechanism that manipulates cartridges and/or seals the breech.

Air Gun - a gun that uses compressed air or gas to propel a projectile also called air rifle, pellet rifle, pellet gun, and gun.

Air Resistance - (Drag) decelerates the projectile with a force proportional to the square of the velocity.

Ammunition - shall mean loaded shell rifle, muskets, carbine, shotguns, revolver and pistol from which a bullet, ball, shot, shell or other missiles may be forwarded by means of gun powder or other explosives.

Anvil - An internal metal component in a boxer primer assembly against which the priming mixture is crushed by the firing pin blow.

Anvil Marks - A term generally used by the military for a cartridge with a full metal jacketed bullet or solid metal projectile.

Armalite – occasionally, the home of manufacturing company becomes almost a generic term. It happens with the colt produced M16, which has been designed and develop at Armalite. The Armalite business was formed by Charles Dorchester and George Sullivan in 1950. Armalite employed Eugene Stoner, Chief Engineer and one of the top designers of the country.

Automatic - when the mechanism is so arranged that it will fire continuously when the trigger is depressed.

Automatic Action Type – a firearm design that feeds cartridges fires and ejects cartridge cases as long as the trigger is fully depressed and there is cartridge available in the feed system.

Barrel - the metal tube through which the projectiles travel.

Berthold Schwartz - the inventor of gunpowder. His real name is Constantin Anklitzen, a Franciscan monk in the town of Freiberg in Germany.

Blowback -  In firearm, an automatic and semi-automatic firearm design, that directly utilizes the breech pressure exerted on the head  of the cartridge cases to actuate the mechanism. In ammunition, a leakage of gas re-ward between the case and chamber wall from the mouth of the case.

Bolt Action Type – a firearm in which the breech closure is
(1) in line with the bore at all times,
(2) manually reciprocated to load, unload and cock
(3) and is locked in place by breech bolt lugs and engaging abutments usually in the receiver.

Bore -  the interior of the barrel of a gun or firearm.

Breechface - is the front part of the breechblock that makes contact with the cartridge in a firearm. The breech block (or breechblock) in a gun is what holds a round in the chamber, and absorbs the recoil of the cartridge when the round is fired, preventing the cartridge case from moving.

Broach Cutter - used to create a rifling impression on a barrel.

Broach, Gang – A tool having a series of cutting edges of slightly increasing height used to cut the spiral grooves in a barrel. All groves are cut with a single pass of the broach.

Broach, Single – a non-adjustable rifling cutter that cuts all the grooves simultaneously, and is in a series of increasing dimensions until the desired groove depth is achieved.

Browning, J.M. - born in 1855. Started the production of a single shot rifle that was adopted by Winchester.

Buckshot - coarse lead shot used in shotgun shells. Lead pellets ranging in size from .20 inches to .36 inch diameter normally loaded in shotshells.

Buffer -  in a firearm, any part intended to absorb shock and check recoil.

Bullet - a projectile propelled from the firearm. A metallic or non-metallic cylindrical projectile. Originated from the French word “BOULETTE”, a small ball. In common police par lane, a bullet maybe called “SLUG”.
       
Two Basic Types of Commercial Bullets in Common Used Today.
1. Lead Bullets - are used in almost all revolver ammunition and in some low or medium powder rifle cartridges. Are produced in an automatic swedging machine from extruded wire containing the proper percentage of tin and antimony for hardening.
2. Jacketed Bullets - are used for automatic pistols ammunition and medium and high power rifle ammunition. The most common are those from the blowback- .25 ACP, .380 ACP, 9mm Luger, .45 ACP (Automatic Colt Pistol) and several types of high velocity .30s. These are all made automatically by swedging a cup of metal around a lead core.

      Armor-Piercing Bullets - is pointed flat base bullet with
      gliding metal jacket. The core is of pointed, boat-tailed shape
      and is made of harden tungsten, chrome steel and has a blackened
      tip. Used to penetrate armored cars and vehicles.

      Tracer Bullet - when fired, emit a light red flame from its base,
      there by showing the gunner the trace of flame, the path as well
      as the striking point of the bullet, the flame continuing to burn
      and trace for about 600 yards. These are intended primarily for
      machine gun use and can be seen by day and night. The point of
      the bullet colored red is for identification. These are used only
      in the military service, and were never sold to individuals.
      Should an individual obtain one or more of these cartridges,
      he should at once return it to military control or else dispose
      of these by throwing into a deep river or lake, as they are
      exceedingly dangerous to have around. This should never be
      “Monkeyed” with, and particularly no attempt should be made to
      unload them for examination, as these may ignite and cause
      exceedingly serious burn or fire. The ingredients used in tracer
      and igniter mixtures are confidential.

      Incendiary Bullet - is similar in construction to a tracer bullet,
      but the composition contained in the cavity burns fiercely impact
      with a very hot flame which will quite reliably ignite anything
      that the bullet strikes. For identification purposes the
      incendiary bullet has a light blue color. The same precaution
      should be observed as with tracer cartridges.

      Dum-Dum Bullet - this word and type of bullet were invented by
      British Ordinance force stationed at their arsenal at Dum-Dum,
      India. The British army was engaged in extensive Punitive
      expedition on the Northwest Frontier of India, fighting against
      Afghan and Pathan tribesmen. It soon develop that such a full
      jacketed bullet was of no practical effect against primitive
      natures. So the English made some of these bullets expanding
      by grinding of the nose of the jacketed bullet. These are now
      known as Hallow Point bullet and Soft Point Bullet.

      Gas Check Bullet - to prevent the melting of the base, lead
      bullets intended to be fired at higher velocity have their gases
      protected with a small copper cups. The bullet is casts with a
      slightly tape-ring base, and the copper gas chock is then pressed
      lightly on the bore, the cup remaining on the bullet when it
      is fired.

      Wad Cutter Bullet - a cylindrical bullet design having a sharp
      shouldered nose intended to cut target paper clearly to
      facilitate easy and accurate soaring.

      Wax Bullet - a bullet made from paraffin and other wax
      preparation usually used for short range indoor target shooting.

      Marks Found Of Fired Bullets
      1. Landmarks -  depressed portion caused by the lands.
      2. Groove Marks -  raised on elevated portions caused by the
         grooves.
      3. Skid Marks -  when the bullet enters the rifled bore from
         a stationary position and is forced abruptly into the
         rifling, its natural tendency is to go straight toward
         before encountering the regular rifling twist.
      4. Slippage Marks -  bullets fired from a worn-out barrel,
         oily barrels and slightly oversized bullets.
      5. Shaving Marks -  most commonly these marks are found on the
         bullets  fires from  a revolver due to a poor alignment of
         the cylindrical with the bore.

      Identification of a Bullet - Principles
      1. No two barrels are microscopically identical as the surfaces
         of their bores all possess individual and characteristics
         on their own.
      2. When a bullet is fired from a rifled barrel, it becomes
         engraved by the riflings and this engraving will vary in
         its minute details with every individual bore. So it happens
         that the engravings on the bullet fired from one barrel will
         be different from that on a similar bullet fired from another
         barrel. And conversely the engraving on bullets fired from
         the same barrel will be the same.
      3. Every barrel leaves its thumb marks on every bullet which
         is fired through it, just as every breech face leaves its
         thumb marks on the base of every fired cartridge case.

      Test Bullet - a bullet fired from a bullet recovery system for
      comparison analysis.

Bullet Recovery System - Any method which will allow the undamaged recovery of a fired bullet. Differing systems are needed for different cartridges depending upon bullet composition, jacket thickness, and velocity. Water tanks and cotton boxes are most commonly in use.

Bullet Splash - The spatter and fragmentation of a bullet upon impacting a hard surface.

Bullet Wipe - The discolored area on the immediate periphery of a bullet hole, caused by bullet lubricant, lead, smoke, bore debris, or possible jacket material. Sometimes called "Burnishing" or
"Leaded Edge".

Button – a hardened metal plug, called a button, with a rifled cross-section configuration. It is pushed or pulled through a drilled and reamed barrel so as to cold form the spiral grooves to the desired depth and twist. When the carbide button was first introduced it was described as a SWAGING PROCESS or SWAGED RIFLING.

Caliber - the diameter of the bore of a rifled firearm. The caliber is usually expressed in hundredths of an inch or millimeters.

- Land to Land - the way to determine the caliber of a gun is to measure the diameter of the bore from land to land.

Cane gun, Knife pistols - many devices primarily designed for other purposes will have a gun mechanism incorporated in them. (also known as FREAKISH DEVICE)

Cannelure - a circumferential groove generally of a knurled or plain appearance on a bullet or cartridge. These three uses including crimping, lubrication, and identification.

Cartridge - a term to describe a complete un-fired unit, consisting of bullet, primer, cartridge case, and gunpowder.

      Test Cartridge Case - a cartridge case obtain while test firing
      a firearm in a laboratory to be used for comparison or analysis.

      Function Of Cartridge Cases
      1. It holds the bullet gunpowder and primer.
      2. It serves as a water proof container for the gunpowder.
      3. It prevents the escape of gases to the rear.

      Marks Found on Cartridge Cases
      1. Firing pin impression – the indentation in the primer of a
         tentative cartridge case or in the rim of a rimface
         cartridge case cause when it is struck by the firing pin.
      2. Breechface Markings – negative impression of the breechface
         of the firearm found on the head of the cartridge case
         after firing.
      3. Chamber Marks – individual microscope marks placed upon a
         cartridge case by the chamber wall as a result of any of
         the following:
               a. Chambering
               b. Expanding during firing
               c. Extraction
      4. Extractor Marks – toolmarks produced upon a cartridge case
         form contact with the extractor. These are usually found on
         or just ahead of the rim.
      5. Ejector Marks – toolmarks produced upon a cartridge or
         cartridge case on the head, generally at or near the rim,
         form contact with the ejector.

Cape Gun – a doubled-barreled shoulder arm with barrel side by side: one being a smooth bore and the other being rifled.

Case Head - The base of the cartridge case which contains the primer.

Cast-Off - the off-set of the butt of a firearm to the right-handed shooter and to the right for a left-handed shooter.

Cast-On - the offset of the butt of a firearm to the left for a right-handed shooter and to the right for a left-handed shooter.

Chamber - the rear part of the barrel bore that has been formed to accept a specific cartridge. Revolver cylinders are multi-chambered.

Cock -  place a firing mechanism under a spring tension. Raise the cock of (a gun) in order to make it ready for firing.

      Full Cock - the position of the hammer or strike when the
      firearm is ready to fire.

Compensator - (MuzzleBrake) a device attached to or integral with the muzzle end of the barrel to utilize propelling gases for counter-recoil.

CETME - Centro dos Studios Technicos de Materiales Especiales. This is a Spanish government weapon development agency, based in Madrid.

Class Characteristics - Are those characteristics which are determinable only after the manufacture of the firearm. They are characteristics whose existence is beyond the control of man and which have a random distribution. Their existence in the firearms is brought about by the tools in their normal operations resulting in wear and tear, abuse, mutilation, corrosion, erosion, and other fortuitous causes.

Classification of Cartridge According to Rim
      1. Rimmed Type - the diameter of the rim is greater than the
         diameter of the body of the cartridge case. e.g. caliber
         .38 and caliber .22.
      2. Semi-Rimmed Type- the diameter of the rim is slightly
         greater than the diameter of the body of the cartridge case.
         e.g. caliber .25. 32 auto. Super .38.
      3. Rimless Type - the diameter of the rim is equal to the body
         of the cartridge case. e.g. caliber .5.56mm, .30, .9mm, .45.
      4. Rebated Type- the diameter of the rim is smaller than the
         body of the cartridge case. e.g. caliber 8mm x 59.
      5. Belted Type - there is a protruding metal around the body
         of the cartridge case near the rim. e.g. caliber 338 magnum
         13.9 x 39

Colt - Samuel Colt was born in July 1814 in was to be instrumental in making the revolver a practical type of pistol.

Cylinder - storage for ammunition in a revolver, the cylinder rotates as the action is cocked.

DAMSCUS - an obsolete barrel making process the barrel is formed by twisting or braiding together steel and iron wires or bars. Sometimes called LAMINATED BARREL.

Derringer, Henry - born at the beginning of the 19th century. Worked at Philadelphia where he manufactured Pocket Pistol.

Drilling - refers to a combination gun that has three barrels.

Ejector Rod - a metal rod used to help with the removal of the cartridges.

Energy Bullet - the capacity of a projectile to do work.

Firearms Identification - a discipline mainly concerned with determining whether a bullet or cartridge was fired by a particular weapon.

Firing Pin - is a lightweight part, which serves to transfer energy from a spring-loaded hammer to the primer, while a striker is usually heavier, and is directly connected to the spring providing
the energy to impact the primer.

Flare guns - used in cases such in sending signals and enabling to see enemies in the dark.

Forensic Ballistics - A scientific study of firearm identification with the use of laboratory examination. The subject gives emphasis on the study of ammunition, projectiles, gunpowder, primer, and explosives, including the use of the bullet comparison microscope. It also deals with the principles in the microscopic and macroscopic examination of firearm evidence and the preparation of reports for legal proceedings in the solution of cases involving firearms.

      Types of Problems in Forensic Ballistics
      1. Given a bullet to determine the caliber and type of firearm
         from which it was fire.
      2. Given fired cartridge case, to determine the caliber and
         type of firearm from which it was fired.
      3. Given a bullet and a suspected firearm, to determine whether
         or not the bullet was fired from the suspected firearm.
      4. Given a fired cartridge case a suspected firearm, to determine
         whether or not the cartridge was fired from the suspected
         firearm.
      5. Given two or more bullets, to determine whether or not they
         were fired from only one firearm.
      6. Given two or more cartridge cases, to determine whether or
         not they were fired.

      Equipments used In A Ballistics Laboratory
      1. Comparison Microscope - This valuable instrument is specially
         designed to permit the firearm examiner to determine the
         similarity and dissimilarity between two fired bullets or
         two fired cartridge cases by simultaneously observing their
         magnified image. It is actually two microscope couple together
         with a single or two eye piece, so that when one looks through
         this comparison eye piece, he is seeing one half of what is
         under the other – in other words, half of the evidence bullet
         and half of the test bullet.
      2. Stereoscope Microscope - This is generally used in the
         preliminary examination of fired bullets and fired shells.
         To determine the location of the extractor marks and ejector
         marks for orientation purposes. It can be used also in one
         close-up examination of tampered serial numbers of firearms.
      3. Comparison Projector - CP6 This is generally used in the
         preliminary examination of fired bullets and fired shells.
         To determine the location of the extractor marks and ejector
         marks for orientation purposes. It can be used also in one
         close-up examination of tampered serial numbers of firearms.
      4. Bullet Recovery Box - For obtaining best fired bullet or
         test fired cartridge cases from the suspected firearms
         submitted to the ballistics laboratory. In test firing
         suspected firearms, it is standard procedure to used
         ammunition that are of the same caliber, make or brand and
         manufactured in the same year with that of the evidence
         bullet or shell.
         Water is one of the means to obtain test bullets and test
         shells because the microscope marks on the cylindrical or
         peripheral surface of the bullets are preserved for good
         used. The same is true with cotton.
      5. Measuring Projector - MP6 This projector determines the
         width of the lands, width of grooves, diameter and twist
         of fired bullets.
      6. Verneir Caliper - This instrument determines the bullet
         diameter and barrel length.
      7. Analytical Balance - This more or less determines the weight
         of the bullets, shots and pellets for possible type, caliber
         and make for firearm from which they were fired.
      8. Taper Gauge - Used for determining the diameter of the bore
         of the firearms.
      9. Onoscope - For examining the interior surface of the barrel.
      10.Helixometer - For measuring the pitch of the rifling. Pitch
         of rifling is the distance advanced by the rifling in one
         complete turn or a distance traveled by the bullet in one
         complete turn.
      11.Chronograph - For determining the speed of the bullet or
         the muzzle velocity of the bullet.

Fouling - the residual deposits remaining in the bore of  a firearm after firing.

Garand, John C. - was born in North Carolina in 1818. Developed the hang-ranked machine gun. A development of Duver Gatling type of machine gun.

Gas Guns – these will be found in all shapes and sizes and used for firing tear gas and other forms of disabling gases.

Gas Operated - an automatic or semi-automatic firearm in which the propellant gases are used to unlock the breech bolt and then to complete the cycle of extracting and expecting.

Gas Port - an opening in the wall of a barrel to allow gas to operate a mechanism or reduce recoil.

Grip - handle of the handgun.

Gunpowder - any of the various powder used in firearms as a propellant charge.

      Types of Gunpowder
      1. Black powder - consists of the jet black and rather shiny
         grains. Although black powder has been in used for about
         six centuries, and although methods of manufactured are
         naturally led to greater efficiency in action, its
         composition has remained practically the same in all
         countries.
      2. Smokeless Powder - a mixture of nitrocellulose 60 parts,
         nitroglycerine 35 parts and Vaseline 5 parts. These
         substances are almost entirely smokeless in action. They are
         all given the generic term of nitro powders and are legion in
         number. All nitro powders used 2. in rifles, pistols, and
         revolvers are a gelatinized powder that is they are made by
         forming dough into sticks or grains. The identification of
         partially burnt powder grains may become a matter of vital
         importance, since such grains maybe found around the entrance
         hole of a wound, and it will obviously help if the type of
         powder can be identified from these unburnt grains.

Hammer - part that strikes the primer to cause ignition.

Hammerli, Johann Ulrich - hammerli weapons have always been the epitome of Swiss precision Engineering ability.

Handgun - a revolver or a pistol.

Harpoon Guns - barbed spear in hunting large fish.

Headspace - is the distance measured from the part of the chamber that stops forward motion of the cartridge (the datum reference) to the face of the bolt.

Headstamp - numerals, letters, and symbols stamped into the head of the cartridge case or shotshell to identify the manufacture caliber gauge or give additional information.

Heckler and Kock – Edmond Heckler has been a plant manager with Mauser, and Alex Siedel a designer with Mauser.

Hook – a cutting tool which cuts has a hook shape and only cuts one groove at a time.

Keyhole - an oblong or an oval hole in a target that is produced by an unstable bullet striking the target at an oblique angle to the bullets. Longitudinal axis.

Leading - the accumulation of lead in the bore of a firearm from the passage of lead shot or bullet. Also called METAL FOULING.

Lever Action Type – a design wherein the breech mechanism is cycled by an external lever generally below the receiver.

Liberator – made by the US government for use in occupied countries in Europe during the recent war and fired the .45ACP cartridge, single shot and smooth bore.

Lubaloy - is a wrought copper alloy that is composed mainly of copper and zinc. In 1922, the Western Cartridge Company introduced a copper-washed bullet jacketing called Lubaloy which stands for a lubricating alloy. Lubaloy replaced standard bullet jacketing which had been cupro-nickel coated steel or solid cupro-nickel.

Luger, George - was born in Australia in 1849. he did lasting designed work in connection with 9mm Parabellum cartridge.

Machine Gun Type – primarily used only in military combat and will seldom be encountered by the firearms technician.

Machine Markings - a cross section of a gun barrel will show small grooves or striations all along with the lands and grooves.

Marlin, John Mahlon - New Haven, Connecticut manufacturer of lever action rifle, 1800’s.

Mauser - Paul and Wilhelm brothers produced parts of the rifle which had been adopted by the German government in 1871.

Mossberge, Oscar - born in Sweden in 1866 and went to the United States. The maker of high quality .22 rifles. Sporting rifles and pump action shotguns.

Mossin, Sergei - Colonel of Russia Army. Designated in Russian Service Rifle in 1891.

Multi –Barreled guns – in particular, one will find guns having the three or four barrels are mounted in one receiver. Some may have a combination of several different gauges of shotguns, or a combination of shotgun barrels and rifle barrel.

Muzzle - the end of the barrel through which the bullet exits.

Muzzle Energy - is the kinetic energy of a bullet as it is expelled from the muzzle of a firearm. It is often used as a rough indication of the destructive potential of a given firearm or load.

Nambu, Kijiro - an army gun officer designer. His first design was produced by the Kayoba Factory in 1904.

Paradox - an obsolete barrel designed in which the major length of the barrel is smooth and last few inches are rifled.

Pen Gun -  a small caliber firearm shaped like a pen or pencil.

Powder - commonly used term for the propellant in a cartridge or shotshell.

Pressure - in a firearm, the force developed by the expanding gasses generated by the combustion of the propellant.

Primer - The ignition components of cartridge primers are used for igniting prominent. A blow from the firing pin of the firing cup compresses the priming composition to detonate. This detonation
produces a flame that passes through the vent of flesh hole in the cartridge case, igniting the gunpowder.

      Composition of a Primer
      1. Potassium Chlorate - 45%
      2. Antimony Sulfide         - 23%
      3. Fulminate of Mercury - 32%

Proofmark - a distinctive symbol stamped into the metal of the barrel or other parts of a firearm to indicate that testing of the part bearing the stamp by firing proof loads has been carried out.

Proof Test - is a form of stress test to demonstrate the fitness of a load-bearing structure. The firing of a deliberate overload to test the strength of a firearm barrel an action.

Rachet - a notched wheel on the rear of a revolver cylinder to rotate when a force is applied by a level hold a hand.

Recoil - (often called knockback, kickback or simply kick) is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gases (ejecta), according to Newton's third law.

Reload - a cartridge, which has been reassembled with a new primer, powder and or other components.

Repeating Arms – this type is loaded with more than cartridge into the chamber when it is fired rather than having to perform this operation by hand.

Resizing - the reduction in diameter of a fire cartridge case to unfired diameter by forcing it into a smaller size than the fired case.

Ricochet - is a rebound, bounce or skip off a surface, particularly in the case of a projectile.

Rifling - refers to helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis.

      Types of Riflings
      1. Steyr Type - four lands, four grooves, right hand twist and
         lands or equal widths ( 4-R-G=L) used in earlier
         self-loading pistols.
      2. Smith and Wesson Type - five lands and five grooves, right
         hand twist and lands of equal width (5-R-G=L)
      3. Browning Type- six lands, six grooves, right hand twist,
         narrow lands and broad grooves. (6-R-G-2x)
      4. Colt Type- six lands and six grooves, left hand twist, narrow
         lands and broads grooves. (6-L-G-2x)
      5. Webley Type- seven lands, seven grooves, right hand twist,
         narrow lands and broad grooves. (7-R-G3x)
      6. Army Type- four lands and four grooves, right hand twist,
         narrow lands and broad grooves. ( 4-R-G3x)

Round -  a military term for a cartridge.

Scrape – a cutting tool that cuts two opposing grooves at a time.

Shocking Power - the ability of a projectile to dissipate its kinetic energy effectively in a target.

Shot - a small ball or pellet of lead, a number of which are loaded in a cartridge and used for one charge of a shotgun.

      Birdshot - the smallest size of shot for sporting rifles or other guns.

Shotshell - a cartridge containing projectile designed to be fired in a shotgun. The cartridge body may be metal, plastic or paper.

Semi-Automatic Type – A firearm requiring a separate pull of the trigger for each shot fired, and which uses the energy of discharge to perform a portion of the operating or firing cycle.

Serial Number - a number applied to a firearm in order to identify the individual firearm.

Shell - an explosive artillery projectile or bomb.

      Identification of Shells - Principles
      1. The breech face and striker of every single firearm leave
         microscopically individualities of their own.
      2. The firearm leaves its “fingerprints” or “thumb mark” on
         every cartridge case which it fires.
      3. The whole principle of identification is based on the fact
         that since the breech face of every weapon must be
         individually distinct, the cartridge cases which it fires are
         imprinted with this individuality. The imprint on all cartridge
         cases fired from the same weapon are always the same, those
         on cartridge cases fired form different weapons must always
         be different.

Shotgun - a smooth-bore gun for firing small shot at short range.
   a. Single Barreled shotgun – it is loaded with a single shotgun
      cartridge, closed. Fired and then re-loaded by the shooter.
   b. Double barreled shotgun – the two barrels may be side by side
      or they may be one over the other. Each barrel may have its
      own trigger.
   c. Pump action shotgun - operates in the same manner as a slide
      action rifles, by means of sliding lever under the barrel.
   d. Auto loading shotguns - these are the same as auto-loading or
      self-loading rifles in that the recoil action reloads the gun
      form the magazine without any effort on the part of the shooter.

SIG - (SCHWEIZERISCHE INDUSTRIE CESSELSHALF) adopted by the Swiss government as their standard service weapon. The company started to produced railway engines and carriage in 1853.

Sidelock – A design in which the firing mechanism is attached to a sideplate rather than being integral with the frame.

Sight - a device used for aiming.

Silencer - a device attached to the barrel of the firearm to reduce the noise of discharge. Also called SOUND SUPPRESSOR.

Single Shot Firearms – those type of firearms that are designated to shoot only one shot.

Slide Action Type – a firearm that features a movable forearm which is manually actuated in motion parallel to the barrel by the shooter. Forearm motion is transmitted to a breech blot assembly which performs all the functions of the firing cycle assigned to it by the design. Also known as PUMP ACTION.

Sling - a strap fastens to a firearm to assist in carrying or to steady it during firing. A sling may also refer to a projectile weapon typically used to throw a blunt projectile such as a stone, clay or lead "sling-bullet".

Slug - a projectile generally fired from a shotgun either one large piece of lead or several smaller caliber pieces.

      Rifled Slug - a simple projectile in spiral grooves and hollow
      base, intended to use in shotgun. The slug will rotate, and
      thus, reach its target much more accurate.

Smith and Wesson - Horace Smith and Daniel B. Wesson formed a partnership in 1852. They manage by producing what is probably the best double-action revolver in the world. (Daniel Wesson left the company to set up his own firearm business).

Smoke Ring - the circular gray deposits around the face of the chamber of a revolver produced by gun powder residues upon discharge.

Stock - also known as a shoulder stock, a buttstock, or simply a butt is a part of a rifle or other firearm, to which the barrel and firing mechanism are attached, that is held against one's shoulder
when firing the gun.

Striations - (Striae) When a bullet is fired through a rifled barrel, the raised and lowered spirals of the rifling etch fine grooves called "striations" into the bullet.

      Characteristics of Striations Depend Upon The ff: Factors
      1. The size and shape of the microscopic irregularities on
         the acting tool.
      2. The original surface smoothness of the object acted upon.
      3. Relative hardness of the two materials.
      4. Speed of application or rate of relative motion.
      5. Pressure areas involved
      6. Texture and uniformity of material acted upon.

Submachine Type – is alight, portable machine gun which uses pistol size ammunition. It differs from a pistol in it that has a shoulder stock that may or may not fold but is designed to be fired by the use of both hands.

Swage – an internal mandrel with rifling configuration which forms rifling in the barrel by means of the external hammering. Also known as HAMMER FORGING.

Tattooing - small hemorrhagic marks on the skin produced by the impact of gun powder particles also called STRIPLING.

Thompson, John - born in 1860 in Newport, Kentucky. Designed the Thompson submachine gun in 1920.

Thumb Rest -  a ledge in the grip area of a rifle or handgun in which to rest the thumb of the trigger hand.

Trailing Edge - the edge of a land or groove impression in a fired bullet which is opposites the driving edge of the same land or groove impressions.

Trajectory - the curved path of a projectile from muzzle to target.

Trap Door – An action in which a top-hinged breechblock pivots up and forward to open. Locking on this action is accomplished by a cam located at the rear of the breechblock that fits into a mating recess. Also known as a CAM LOCK.

Trigger - is a mechanism that actuates the firing of firearms.

Trigger Guard - trigger guard is a loop surrounding the trigger of a firearm and protecting it from accidental discharge.

Trigger Pull - the amount of force, which must firearm to cause sear release.

Tokarev, Fedor - born in Egorlikshaya in 1971. Designed the service pistol of the Soviet forces.

Tool Marks Identification - is a discipline of forensic science which has, as its primary concern to determine if a tool mark was produced by a particular tool.

      Two General Type of Tool Marks
      1. Impression Type - which as its name implies a little more than
         a bent. A pry-bar may leave an impression type-mark on a window
         frame to which is applied. The shape and the size of the mark,
         plus irregularities cause by nicks or breaks in the pry-bar,
         may be such as to permit a positive statement as to its source.
      2. Striated Tool Mark- is left by a tool scrapping over an object
         or surface softer than him. Thus, a pry-bar which slips during
         the application may scraped over the jamb of a door, leaving
         striate. Tin Snips or Bolt Cutter have blades which frequently
         leave striate on the edges of metal cut. An axe will leave
         striate on wood chips, as well as the auger or blade of a
         plane. Mechanical tool as a planner, joiner, and lathe all
         have blades and edges which leaves striate on chips, shaving
         and stock being worked. Many examples should be given but
         these are typical if the tool most commonly encountered in
         the criminal investigations. Striated marks are often referred
         to a “friction marks”, abrasion marks or “scratched marks”.

Tools – there are a number of tools using cartridges that are designed to drive studs, punch holes or cut tables. Such tools may be encountered in the investigation of an accident.

Traps – these are designed to be set in the woods and left where animals will encounter them. They may fire a bullet or a poisoning charge, depending on their construction.

Trigger - small lever that is pulled or squeezed to start the firing process.

Trigger Guard - piece that surrounds the trigger to protect it from being accidentally squeezed or bumped.

Velocity - the speed of the projectile at a given point along its trajectory.

Vierling - A four-barreled gun, typically with two identical shotgun barrels and with two rifle barrels of differing calibres. Built primarily in Germany and Austria.

Walther, Carl - developed a reliable small caliber automatic pistol in 1866.

Walker Test - the original chemical test for the detection of spatial distributions of nitrites in gun powder residue.

Winchester, Oliver - he led the formation of the Winchester Company.

Types Of Cartridge Case According To Location Of Primer
1. Pin-Fire Cartridge - the pin extends radially through the bead of the cartridge case into the primer. This type of cartridge is no longer use.
2. Rim-Fire Cartridge- the priming mixture is placed in the cavity formed in the rim of the head of the cartridge case.
3. Center-Fire Cartridge- the primer cup is force to the middle portion of the head of the cartridge case.
4. Percussion - a means of ignition of propellant change by a mechanical blow against the primer or percussion cap.
a. Low Power - a cartridge giving a muzzle velocity of less than 1850 ft/sec.
b. High Power- a cartridge giving a muzzle velocity of between 1925 and 2500 ft/sec.
c. High Intensity- a cartridge giving a muzzle velocity over 2500 ft/sec.

Yaw - the angle between the longitudinal axis of a projectile and the line of the projectile trajectory.

Zip guns - these may be in any form, since the name has been applied to all homemade guns. A great many of this class will be found to be exceedingly clever mechanisms and most effective weapon.

Zwilling - European term for a double barreled shoulder arm with one rifle and one smooth bore barrel.


Related:

Basic Gun Terminology

RA 10591 Comprehensive Firearms and Ammunition Regulation Act

Ammunition

History of Firearms (Timeline)